Gamma-ray stereotactic radiotherapy system，also known as gamma knife，has a unique position in radiotherapy. The early development of gamma knife has experienced many changes in focusing mode and therapeutic scope and experienced some challenges. Image-guided gamma knife is born in response to clinical needs，which makes up for the function shortcoming of old gamma knife and ushers the development of gamma knife into a new era. The head gamma knife treatment opens a non-invasive fractional mode，the body gamma knife treatment realizes higher accuracy，and the treatment effect is also improved. With the continuous diversified development of image-guided technology and function，image-guided gamma knife has become an independent and mainstream radiotherapy device comparable to the medical linear accelerator. It should be used in more clinical applications.